1. Field of the Invention
The present invention relates to oil and gas wells. More particularly, the present invention relates to a method and apparatus for predicting the state properties of a multi-phase fluid at any point within the fluid conduit of an oil and gas well.
2. Description of the Related Art
Oil and gas have been extracted from the subsurface of the earth for many decades. Well holes are drilled into the earth until a reservoir of fluid is reached. The underground fluid is then extracted and refined for various purposes. As with most oil and gas wells, the extracted fluid is a multi-phase mixture of oil, water, and gas. The gas itself is in two forms, free gas and gas that is in solution either with the oil or with the water.
The monitoring of the production of fluid from oil and gas wells continues to be an important activity. Not only is monitoring necessary for obvious economic reasons, but also as an indicator of serious problems, such as leaks in the piping making up the well.
Currently, oilfield service companies physically insert a measuring tool into the flow conduit of a well to measure fluid characteristics such as temperature, pressure, and total flow rate. The process of physically measuring and recording the flow in a well hole is called production logging. At best, a production log may provide an accurate snapshot of production information at the particular time that the measurements are made. However, this information can change relatively quickly, especially in a well with multi-zone production where the production from one zone can affect the production in another. There are several other problems involved with prior art production logging methods. First, the measuring device that is used has a finite size, so it disturbs the flow that it is trying to measure and introduces error into the measurement and subsequent calculations. Second, the measuring device must be calibrated in the well. Unfortunately, the well cannot be producing while the measuring device is being calibrated so the calibration period results in a loss of revenue for the oil well owner. Consequently, current production logging methods are not entirely satisfactory.
There is, therefore, a need, therefore, of a method and/or a device for production logging that can measure accurately the production capacity of an oil and gas well without disturbing the fluid flow during measurement. There is also a need in the art for a method that does not require the well to be shut down during calibration of the measuring instruments. It is an object of the present invention to solve the problems inherent in the prior art methods. It is a further object of the present invention to utilize existing equipment on the wellhead to enable remote monitoring of well production.